//! mdevctl is a utility for managing and persisting devices in the mediated device framework of
//! the Linux kernel.  Mediated devices are sub-devices of a parent device (ex. a vGPU) which can
//! be dynamically created and potentially used by drivers like vfio-mdev for assignment to virtual
//! machines.
//!
//! See `mdevctl help` or the manpage for more information.

use anyhow::{anyhow, ensure, Context, Result};
use log::{debug, warn};
use std::cmp::Ordering;
use std::collections::BTreeMap;
use std::fs;
use std::io::Read;
use std::path::PathBuf;
use std::vec::Vec;
use structopt::StructOpt;
use uuid::Uuid;

use crate::callouts::*;
use crate::cli::{LsmdevOptions, MdevctlCommands};
use crate::environment::{DefaultEnvironment, Environment};
use crate::logger::logger;
use crate::mdev::*;

mod callouts;
mod cli;
mod environment;
mod logger;
mod mdev;

#[cfg(test)]
mod tests;

/// Format a map of mediated devices into a json string
fn format_json(devices: BTreeMap<String, Vec<MDev>>) -> Result<String> {
    let mut parents = serde_json::map::Map::new();
    for (parentname, children) in devices {
        let mut childrenarray = Vec::new();
        for child in children {
            childrenarray.push(child.to_json(true)?);
        }
        parents.insert(parentname, childrenarray.into());
    }
    // don't serialize an empty object if there are no devices
    let jsonval = match parents.len() {
        0 => serde_json::json!([]),
        _ => serde_json::json!([parents]),
    };
    serde_json::to_string_pretty(&jsonval).map_err(|_e| anyhow!("Unable to serialize json"))
}

/// convert 'define' command arguments into a MDev struct
fn define_command_helper(
    env: &dyn Environment,
    uuid: Option<Uuid>,
    auto: bool,
    parent: Option<String>,
    mdev_type: Option<String>,
    jsonfile: Option<PathBuf>,
) -> Result<MDev> {
    let uuid_provided = uuid.is_some();
    let uuid = uuid.unwrap_or_else(Uuid::new_v4);
    let mut dev = MDev::new(env, uuid);

    if let Some(jsonfile) = jsonfile {
        let _ = std::fs::File::open(&jsonfile)
            .with_context(|| format!("Unable to read file {:?}", jsonfile));

        if mdev_type.is_some() {
            return Err(anyhow!(
                "Device type cannot be specified separately from {:?}",
                jsonfile
            ));
        }

        let parent = parent
            .ok_or_else(|| anyhow!("Parent device required to define device via {:?}", jsonfile))?;

        let devs = defined_devices(env, Some(&uuid), Some(&parent))?;
        if !devs.is_empty() {
            return Err(anyhow!(
                "Cowardly refusing to overwrite existing config for {}/{}",
                parent,
                uuid.to_hyphenated().to_string()
            ));
        }

        let filecontents = fs::read_to_string(&jsonfile)
            .with_context(|| format!("Unable to read jsonfile {:?}", jsonfile))?;
        let jsonval = serde_json::from_str(&filecontents)?;
        dev.load_from_json(parent, &jsonval)?;
    } else {
        if uuid_provided {
            dev.load_from_sysfs()?;
            if parent.is_none() && (!dev.active || mdev_type.is_some()) {
                return Err(anyhow!("No parent specified"));
            }
        }

        dev.autostart = auto;
        if parent.is_some() {
            dev.parent = parent;
        }
        if mdev_type.is_some() {
            dev.mdev_type = mdev_type;
        }

        if dev.parent.is_none() {
            return Err(anyhow!("No parent specified"));
        }
        if dev.mdev_type.is_none() {
            return Err(anyhow!("No type specified"));
        }

        if dev.is_defined() {
            return Err(anyhow!(
                "Device {} on {} already defined",
                dev.uuid.to_hyphenated().to_string(),
                dev.parent()?
            ));
        }
    }

    Ok(dev)
}

/// Implementation of the `mdevctl define` command
fn define_command(
    env: &dyn Environment,
    uuid: Option<Uuid>,
    auto: bool,
    parent: Option<String>,
    mdev_type: Option<String>,
    jsonfile: Option<PathBuf>,
) -> Result<()> {
    debug!("Defining mdev {:?}", uuid);

    let mut dev = define_command_helper(env, uuid, auto, parent, mdev_type, jsonfile)?;

    /*
        Call Callout::get_attributes() when defining an active device without a config file.
        This function allows callout script to acquire device-specific attributes from sysfs,
        and populate the attrs field correspondingly before the device is defined in the system.
        The device config file will contain the same attributes that were used to start this device。
    */
    if dev.active {
        let attrs = Callout::get_attributes(&mut dev)?;
        dev.add_attributes(&attrs)?;
    }
    Callout::invoke(&mut dev, Action::Define, |dev| dev.define()).map(|_| {
        if uuid.is_none() {
            println!("{}", dev.uuid.to_hyphenated());
        }
    })
}

/// Implementation of the `mdevctl undefine` command
fn undefine_command(env: &dyn Environment, uuid: Uuid, parent: Option<String>) -> Result<()> {
    debug!("Undefining mdev {:?}", uuid);
    let devs = defined_devices(env, Some(&uuid), parent.as_ref())?;
    if devs.is_empty() {
        return Err(anyhow!("No devices match the specified uuid"));
    }
    for (_, mut children) in devs {
        for mut child in children.iter_mut() {
            let _ = Callout::invoke(&mut child, Action::Undefine, |dev| dev.undefine());
        }
    }
    Ok(())
}

/// Implementation of the `mdevctl modify` command
#[allow(clippy::too_many_arguments)]
fn modify_command(
    env: &dyn Environment,
    uuid: Uuid,
    parent: Option<String>,
    mdev_type: Option<String>,
    addattr: Option<String>,
    delattr: bool,
    index: Option<u32>,
    value: Option<String>,
    auto: bool,
    manual: bool,
) -> Result<()> {
    let mut dev = get_defined_device(env, uuid, parent.as_ref())?;
    if mdev_type.is_some() {
        dev.mdev_type = mdev_type;
    }

    if auto {
        dev.autostart = true;
    } else if manual {
        dev.autostart = false;
    }

    match addattr {
        Some(attr) => match value {
            None => return Err(anyhow!("No attribute value provided")),
            Some(v) => dev.add_attribute(attr, v, index)?,
        },
        None => {
            if delattr {
                dev.delete_attribute(index)?;
            }
        }
    }

    Callout::invoke(&mut dev, Action::Modify, |dev| dev.write_config())
}

/// convert 'start' command arguments into a MDev struct
fn start_command_helper(
    env: &dyn Environment,
    uuid: Option<Uuid>,
    parent: Option<String>,
    mdev_type: Option<String>,
    jsonfile: Option<PathBuf>,
) -> Result<MDev> {
    debug!("Starting device '{:?}'", uuid);
    let mut dev: Option<MDev> = None;
    match jsonfile {
        Some(fname) => {
            let contents = fs::read_to_string(&fname)
                .with_context(|| format!("Unable to read jsonfile {:?}", fname))?;
            let val = serde_json::from_str(&contents)?;

            if mdev_type.is_some() {
                return Err(anyhow!(
                    "Device type cannot be specified separately from json file"
                ));
            }

            let parent = parent
                .ok_or_else(|| anyhow!("Parent device required to start device via json file"))?;

            let mut d = MDev::new(env, uuid.unwrap_or_else(Uuid::new_v4));
            d.load_from_json(parent, &val)?;
            dev = Some(d);
        }
        _ => {
            // if the user specified a uuid, check to see if they're referring to a defined device
            if uuid.is_some() {
                let devs = defined_devices(env, uuid.as_ref(), parent.as_ref())?;
                let n = devs.values().flatten().count();
                match n.cmp(&1) {
                    Ordering::Greater => {
                        return Err(anyhow!(
                            "Multiple definitions found for device {}. Please specify a parent.",
                            uuid.unwrap().to_hyphenated().to_string()
                        ));
                    }
                    Ordering::Equal => {
                        // FIXME: use into_values() to consume the iterator and avoid cloning below
                        // when we can require rust 1.54.0
                        let d = devs.values().flatten().next();
                        if let Some(d) = d {
                            // See https://github.com/mdevctl/mdevctl/issues/38
                            // If a user specifies the uuid (and optional parent) of a defined device
                            if mdev_type.is_some() && mdev_type != d.mdev_type {
                                return Err(anyhow!(
                                    "Device {} already exists on parent {} with type {}",
                                    d.uuid.to_hyphenated().to_string(),
                                    d.parent().unwrap(),
                                    d.mdev_type.as_ref().unwrap()
                                ));
                            } else {
                                dev = Some(d.clone());
                            }
                        }
                    }
                    _ => (),
                }
            }

            if dev.is_none() {
                let mut d = MDev::new(env, uuid.unwrap_or_else(Uuid::new_v4));
                d.parent = parent;
                d.mdev_type = mdev_type;
                dev = Some(d);
            }

            if let Some(ref d) = dev {
                if d.mdev_type.is_some() && d.parent.is_none() {
                    return Err(anyhow!("can't provide type without parent"));
                }
                if d.mdev_type.is_none() || d.parent.is_none() {
                    return Err(anyhow!("Device is insufficiently specified"));
                }
            }
        }
    }
    dev.ok_or_else(|| anyhow!("Unknown error"))
}

/// Implementation of the `mdevctl start` command
fn start_command(
    env: &dyn Environment,
    uuid: Option<Uuid>,
    parent: Option<String>,
    mdev_type: Option<String>,
    jsonfile: Option<PathBuf>,
) -> Result<()> {
    let mut dev = start_command_helper(env, uuid, parent, mdev_type, jsonfile)?;

    Callout::invoke(&mut dev, Action::Start, |dev| dev.start()).map(|_| {
        if uuid.is_none() {
            println!("{}", dev.uuid.to_hyphenated());
        }
    })
}

/// Implementation of the `mdevctl stop` command
fn stop_command(env: &dyn Environment, uuid: Uuid) -> Result<()> {
    debug!("Stopping '{}'", uuid);
    let mut dev = MDev::new(env, uuid);
    dev.load_from_sysfs()?;

    Callout::invoke(&mut dev, Action::Stop, |dev| dev.stop())
}

/// convenience function to lookup a defined device by uuid and parent
fn get_defined_device<'a>(
    env: &'a dyn Environment,
    uuid: Uuid,
    parent: Option<&String>,
) -> Result<MDev<'a>> {
    let devs = defined_devices(env, Some(&uuid), parent)?;
    if devs.is_empty() {
        return match parent {
            None => Err(anyhow!(
                "Mediated device {} is not defined",
                uuid.to_hyphenated().to_string()
            )),
            Some(p) => Err(anyhow!(
                "Mediated device {}/{} is not defined",
                p,
                uuid.to_hyphenated().to_string()
            )),
        };
    } else if devs.len() > 1 {
        return match parent {
            None => Err(anyhow!(
                "Multiple definitions found for {}, specify a parent",
                uuid.to_hyphenated().to_string()
            )),
            Some(p) => Err(anyhow!(
                "Multiple definitions found for {}/{}",
                p,
                uuid.to_hyphenated().to_string()
            )),
        };
    } else {
        let (parent, children) = devs.iter().next().unwrap();
        if children.len() > 1 {
            return Err(anyhow!(
                "Multiple definitions found for {}/{}",
                parent,
                uuid.to_hyphenated().to_string()
            ));
        }
        return Ok(children.get(0).unwrap().clone());
    }
}

/// Get a map of all defined devices, optionally filtered by uuid and parent
fn defined_devices<'a>(
    env: &'a dyn Environment,
    uuid: Option<&Uuid>,
    parent: Option<&String>,
) -> Result<BTreeMap<String, Vec<MDev<'a>>>> {
    let mut devices: BTreeMap<String, Vec<MDev>> = BTreeMap::new();
    debug!(
        "Looking up defined mdevs: uuid={:?}, parent={:?}",
        uuid, parent
    );
    for parentpath in env.persist_base().read_dir()? {
        let parentpath = parentpath?;
        let parentname = parentpath.file_name();
        let parentname = parentname.to_str().unwrap();
        if (parent.is_some() && parent.unwrap() != parentname) || !parentpath.metadata()?.is_dir() {
            debug!("Ignoring child devices for parent {}", parentname);
            continue;
        }

        let mut childdevices = Vec::new();

        for child in parentpath.path().read_dir()? {
            let child = child?;
            if !child.metadata()?.is_file() {
                continue;
            }

            let path = child.path();
            let basename = path.file_name().unwrap().to_str().unwrap();
            let u = Uuid::parse_str(basename);
            if u.is_err() {
                warn!("Can't determine uuid for file '{}'", basename);
                continue;
            }
            let u = u.unwrap();

            debug!("found mdev {:?}", u);
            if uuid.is_some() && uuid != Some(&u) {
                debug!(
                    "Ignoring device {} because it doesn't match uuid {}",
                    u,
                    uuid.unwrap()
                );
                continue;
            }

            let mut f = fs::File::open(path)?;
            let mut contents = String::new();
            f.read_to_string(&mut contents)?;
            let val = serde_json::from_str(&contents)?;
            let mut dev = MDev::new(env, u);
            dev.load_from_json(parentname.to_string(), &val)?;
            dev.load_from_sysfs()?;

            childdevices.push(dev);
        }
        if !childdevices.is_empty() {
            devices.insert(parentname.to_string(), childdevices);
        }
    }
    Ok(devices)
}

/// Implementation of the `mdevctl list` command
fn list_command(
    env: &dyn Environment,
    defined: bool,
    dumpjson: bool,
    verbose: bool,
    uuid: Option<Uuid>,
    parent: Option<String>,
) -> Result<()> {
    let output = list_command_helper(env, defined, dumpjson, verbose, uuid, parent)?;
    println!("{}", output);
    Ok(())
}

/// convert 'list' command arguments into a text output
fn list_command_helper(
    env: &dyn Environment,
    defined: bool,
    dumpjson: bool,
    verbose: bool,
    uuid: Option<Uuid>,
    parent: Option<String>,
) -> Result<String> {
    let mut devices: BTreeMap<String, Vec<MDev>> = BTreeMap::new();
    if defined {
        devices = defined_devices(env, uuid.as_ref(), parent.as_ref())?;
    } else {
        debug!("Looking up active mdevs");
        if let Ok(dir) = env.mdev_base().read_dir() {
            for dev in dir {
                let dev = dev?;
                let fname = dev.file_name();
                let basename = fname.to_str().unwrap();
                debug!("found defined mdev {}", basename);
                let u = Uuid::parse_str(basename);

                if u.is_err() {
                    warn!("Can't determine uuid for file '{}'", basename);
                    continue;
                }
                let u = u.unwrap();

                if uuid.is_some() && uuid != Some(u) {
                    debug!(
                        "Ignoring device {} because it doesn't match uuid {}",
                        u,
                        uuid.unwrap()
                    );
                    continue;
                }

                let mut dev = MDev::new(env, u);
                if dev.load_from_sysfs().is_ok() {
                    if parent.is_some() && (parent != dev.parent) {
                        debug!(
                            "Ignoring device {} because it doesn't match parent {}",
                            dev.uuid,
                            parent.as_ref().unwrap()
                        );
                        continue;
                    }

                    let _ = dev.load_definition();

                    if !dev.is_defined() {
                        if let Ok(attrs) = Callout::get_attributes(&mut dev) {
                            let _ = dev.add_attributes(&attrs);
                        }
                    }

                    let devparent = dev.parent()?;
                    if !devices.contains_key(devparent) {
                        devices.insert(devparent.clone(), Vec::new());
                    };

                    devices.get_mut(devparent).unwrap().push(dev);
                };
            }
        }
    }

    // ensure that devices are sorted in a stable order
    for v in devices.values_mut() {
        v.sort_by_key(|e| e.uuid);
    }

    let output = match dumpjson {
        true => {
            // if specified to a single device, output such that it can be piped into a config
            // file, else print entire heirarchy
            if uuid.is_none() || devices.values().flatten().count() > 1 {
                format_json(devices)?
            } else {
                let jsonval = match devices.values().next() {
                    Some(children) => children
                        .first()
                        .ok_or_else(|| anyhow!("Failed to get device"))?
                        .to_json(false)?,
                    None => serde_json::json!([]),
                };
                serde_json::to_string_pretty(&jsonval)
                    .map_err(|_e| anyhow!("Unable to serialize json"))?
            }
        }
        false => {
            let ft = match defined {
                true => FormatType::Defined,
                false => FormatType::Active,
            };
            devices
                .values()
                // convert child vector into an iterator over the vector's elements
                .flat_map(|v| v.iter())
                // convert MDev elements to a text representation, filtering out errors
                .flat_map(|d| d.to_text(ft, verbose))
                .collect::<String>()
        }
    };
    Ok(output)
}

/// Get a map of all mediated device types that are supported on this machine
fn supported_types(
    env: &dyn Environment,
    parent: Option<String>,
) -> Result<BTreeMap<String, Vec<MDevType>>> {
    debug!("Finding supported mdev types");
    let mut types: BTreeMap<String, Vec<MDevType>> = BTreeMap::new();

    if let Ok(dir) = env.parent_base().read_dir() {
        for parentpath in dir {
            let parentpath = parentpath?;
            let parentname = parentpath.file_name();
            let parentname = parentname.to_str().unwrap();
            debug!("Looking for supported types for device {}", parentname);
            if parent.is_some() && parent.as_ref().unwrap() != parentname {
                debug!("Ignoring types for parent {}", parentname);
                continue;
            }

            let mut childtypes = Vec::new();
            let mut parentpath = parentpath.path();
            parentpath.push("mdev_supported_types");
            for child in parentpath.read_dir()? {
                let child = child?;
                if !child.metadata()?.is_dir() {
                    continue;
                }

                let mut t = MDevType::new();
                t.parent = parentname.to_string();

                let mut path = child.path();
                t.typename = path.file_name().unwrap().to_str().unwrap().to_string();
                debug!("found mdev type {}", t.typename);

                path.push("available_instances");
                debug!("Checking available instances: {:?}", path);
                t.available_instances = fs::read_to_string(&path)?.trim().parse()?;

                path.pop();
                path.push("device_api");
                t.device_api = fs::read_to_string(&path)?.trim().to_string();

                path.pop();
                path.push("name");
                if path.exists() {
                    t.name = fs::read_to_string(&path)?.trim().to_string();
                }

                path.pop();
                path.push("description");
                if path.exists() {
                    t.description = fs::read_to_string(&path)?
                        .trim()
                        .replace("\n", ", ")
                        .to_string();
                }

                childtypes.push(t);
            }
            types.insert(parentname.to_string(), childtypes);
        }
    }
    for v in types.values_mut() {
        v.sort_by(|a, b| a.typename.cmp(&b.typename));
    }
    Ok(types)
}

/// convert 'types' command arguments into a text output
fn types_command_helper(
    env: &dyn Environment,
    parent: Option<String>,
    dumpjson: bool,
) -> Result<String> {
    let types = supported_types(env, parent)?;
    let mut output = String::new();
    debug!("{:?}", types);
    if dumpjson {
        let mut parents = serde_json::map::Map::new();
        for (parent, children) in types {
            let mut childarray = Vec::new();
            for child in children {
                childarray.push(child.to_json()?);
            }
            parents.insert(parent, childarray.into());
        }

        let jsonval = match parents.len() {
            0 => serde_json::json!([]),
            _ => serde_json::json!([parents]),
        };
        let jsonstr = serde_json::to_string_pretty(&jsonval)
            .map_err(|_e| anyhow!("Unable to serialize json"))?;
        output.push_str(&jsonstr);
    } else {
        for (parent, children) in types {
            output.push_str(&format!("{}\n", parent));
            for child in children {
                output.push_str(&format!("  {}\n", child.typename));
                output.push_str(&format!(
                    "    Available instances: {}\n",
                    child.available_instances
                ));
                output.push_str(&format!("    Device API: {}\n", child.device_api));
                if !child.name.is_empty() {
                    output.push_str(&format!("    Name: {}\n", child.name));
                }
                if !child.description.is_empty() {
                    output.push_str(&format!("    Description: {}\n", child.description));
                }
            }
        }
    }
    Ok(output)
}

/// Implementation of the `mdevctl types` command
fn types_command(env: &dyn Environment, parent: Option<String>, dumpjson: bool) -> Result<()> {
    let output = types_command_helper(env, parent, dumpjson)?;
    println!("{}", output);
    Ok(())
}

/// Implementation of the `start-parent-mdevs` command
fn start_parent_mdevs_command(env: &dyn Environment, parent: String) -> Result<()> {
    let mut devs = defined_devices(env, None, Some(&parent))?;
    if devs.is_empty() {
        // nothing to do
        return Ok(());
    }

    ensure!(devs.len() == 1, "More than one parent found");

    for (_, children) in devs.iter_mut() {
        for child in children {
            if child.autostart {
                debug!("Autostarting {:?}", child.uuid);
                if let Err(e) = Callout::invoke(child, Action::Start, |child| child.start()) {
                    for x in e.chain() {
                        warn!("{}", x);
                    }
                }
            }
        }
    }
    Ok(())
}

/// parse command line arguments and dispatch to command-specific functions
fn main() -> Result<()> {
    logger().init();
    debug!("Starting up");

    let env = DefaultEnvironment::new();
    debug!("{:?}", env);
    // check if we're running as the symlink executable 'lsmdev'. If so, just execute the 'list'
    // command directly
    let exe = std::env::args_os().next().unwrap();
    match exe.to_str() {
        Some(val) if val.ends_with("lsmdev") => {
            debug!("running as 'lsmdev'");
            let opts = LsmdevOptions::from_args();
            list_command(
                &env,
                opts.defined,
                opts.dumpjson,
                opts.verbose,
                opts.uuid,
                opts.parent,
            )
        }
        _ => match MdevctlCommands::from_args() {
            MdevctlCommands::Define {
                uuid,
                auto,
                parent,
                mdev_type,
                jsonfile,
            } => define_command(&env, uuid, auto, parent, mdev_type, jsonfile),
            MdevctlCommands::Undefine { uuid, parent } => undefine_command(&env, uuid, parent),
            MdevctlCommands::Modify {
                uuid,
                parent,
                mdev_type,
                addattr,
                delattr,
                index,
                value,
                auto,
                manual,
            } => modify_command(
                &env, uuid, parent, mdev_type, addattr, delattr, index, value, auto, manual,
            ),
            MdevctlCommands::Start {
                uuid,
                parent,
                mdev_type,
                jsonfile,
            } => start_command(&env, uuid, parent, mdev_type, jsonfile),
            MdevctlCommands::Stop { uuid } => stop_command(&env, uuid),
            MdevctlCommands::List(list) => list_command(
                &env,
                list.defined,
                list.dumpjson,
                list.verbose,
                list.uuid,
                list.parent,
            ),
            MdevctlCommands::Types { parent, dumpjson } => types_command(&env, parent, dumpjson),
            MdevctlCommands::StartParentMdevs { parent } => {
                start_parent_mdevs_command(&env, parent)
            }
        },
    }
}
